1. Field of the Invention
The present invention relates generally to a centrifugal fan, blower or the like, and more specifically, to a centrifugal blower assembly that reduces rumble noise generated during operation.
2. Description of the Related Art
Centrifugal fans or blowers are commonly used in the automotive, air handling and ventilation industries for directing a forced flow of air through a variety of air conditioning components. In a typical centrifugal blower, air is drawn into a housing through an inlet aperture by a rotating blower or fan. This air is then forced around the housing and out an air exit end. Back pressure causes airflow re-circulation back across the cut-off region, causing a rumble noise when the difference in pressure is large near the inlet aperture between exit flow and inlet flow. Various modifications to the housing have been proposed for reducing noise.
Therefore, it is desirable to reduce airflow re-entering back into the fan wheel near the cut-off region, thereby reducing low rumble noise. It is further desirable to reduce noise in the centrifugal blower in an economical manner without affecting the performance of the centrifugal blower.